The present invention relates to a method for tracking a solar generator to the sun, to a control for a solar plant as well as to a solar plant. In particular, the present invention relates to an approach for tracking a solar generator having a plurality of solar modules to the sun based on an electric output quantity of at least part of the solar modules of the solar generator.
Apparatuses for tracking a solar generator to the current position of the sun, so-called trackers, are known in the art, wherein one example is described in DE 20204679 U1. Further, reference is made to DE 102006058845 B3, also showing such a tracker. The drives of such apparatuses guide the solar generators in azimuth and/or elevation direction to the sun, such that at all times a maximum possible solar radiation impinges on the solar generator. For this, such known apparatuses comprise a sensor generating an intensity signal depending on the light impinging thereon, which is provided to a circuit integrated in the control unit, which passes a control signal to a drive of the tracker to effect the respective orientation of the solar generator to the brightest spot in the sky.
Alternatively or additionally to the sensor, the control can control the tracker based on the calculation of sun ephemerides in order to effect respective tracking of the solar generator to the sun. Such a system is described, for example in ES 2 273 576 B1.
Thus, such known tracker systems try to optimize the output power of the solar generator by following the sun cross the sky to obtain maximum sunlight output. By tracking the solar generator, typically, an increase of the output of, for example, +28% in Central Europe up to +54% in Northern Europe can be obtained.
However, the above-described known approaches for tracking a solar generator to the sun, have different disadvantages. The embodiment comprising a sensor for detecting sunlight is disadvantageous, since sufficiently exact position determination and respective control of the tracker system is only possible with clear sky. When it is cloudy, these sensors are less useful. Further, such sensors acquire exact installation at the solar generator or with respect to the solar generator and respective calibration. Further, such positioning sensors are expensive and prone to contamination, such that even with clear sky no sufficiently exact position determination and respective control of the tracker system is given.
Controlling the orientation of the solar generator based on the calculation of sun ephemerides is also disadvantageous. Based on sun ephemerides in connection with the location of the tracker and the time, the position of the sun at the sky can be determined with good accuracy, however, the accuracy depends on the accuracy of the sensors used for determining the position of the solar generator and also on the accuracy of the installation of the solar generators and their adjustment. Further, such systems (see e.g. ES 2 273 576 B1) use an open control loop necessitating initial calibration, e.g. based on a sensor or the short-circuit current. The actual control of the orientation of the solar generator during the day is only effected based on the calculated position of the sun, i.e. without returned positioning signal.